Abstract:

A tongue for a building panel, said tongue is of an elongated shape,
wherein the tongue has at least two protrusions that extend in the same
direction at a first long edge of the tongue, and the protrusions are
bendable in a plane parallel to the upper surface of the tongue and
extending essentially in the parallel plane and, the tongue has a second
long edge, which is essentially straight over substantially the whole
length of the tongue, and, a vertical protrusion is arranged at the upper
side and/or at the lower side of the horizontal protrusions.

Claims:

1. A tongue for a building panel, said tongue is of an elongated shape,
wherein the tongue comprises at least two protrusions that extend in the
same direction at a first long edge of the tongue, and the protrusions
are bendable in a plane parallel to an upper surface of the tongue and
extending essentially in the parallel plane and, the tongue has a second
long edge, which is essentially straight over substantially the whole
length of the tongue, and, a vertical protrusion is arranged at the upper
side and/or at the lower side of the horizontal protrusions.

2. The tongue as claimed in claim 1, wherein the vertical protrusion is
arranged close to or at the tip of horizontal protrusions.

3. The tongue as claimed in claim 1, wherein there is an angle between
the protrusions and a longitudinal direction of the tongue.

4. The tongue as claimed in claim 3, wherein said angle is the same for
said at least two protrusions.

5. The tongue as claimed in claim 1, wherein the protrusions are bow
formed.

6. The tongue as claimed in claim 1, wherein the protrusions are
configured to extend into a displacement groove of the building panel.

7. The tongue as claimed in claim 1, wherein the first long edge of the
tongue comprises a recess at each protrusion.

8. The tongue as claimed in claim 7, wherein the size of the recess is
adapted to the size of the protrusion.

9. The tongue as claimed in claim 8, wherein the shape of the recess is
adapted to the shape the protrusion.

10. The tongue as claimed in claim 1, wherein the essentially straight
edge of the tongue is continuous.

11. The tongue as claimed in claim 1, wherein the upper surface and a
lower surface of the tongue are displacement surfaces.

13. The tongue as claimed in claim 1, wherein tongue is of molded
plastic.

14. The tongue as claimed in claim 13, wherein tongue is made PP or POM,
and reinforced with fibres.

15. The tongue as claimed in claim 1, wherein the building panel is a
floor panel.

16. The tongue as claimed in claim 6, wherein the displacement groove is
made of a different material than a core of the panel.

17. The tongue as claimed in claim 1, wherein the length of the
protrusions is larger than the total width of the tongue, whereby the
total width is the width of the tongue plus the distance from the tongue
body to the tip of the protrusion perpendicular to the length direction
of the tongue.

18. The tongue as claimed in claim 17, wherein the length of the
protrusion is larger than two times the total width of the tongue.

19. The tongue as claimed in claim 1, wherein force to compress the
tongue 1 mm in the width direction per 100 mm length of the tongue is in
the range of about 20 to about 30 N.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a continuation of U.S. application Ser.
No. 11/775,885, filed on Jul. 11, 2007, which is a continuation-in-part
of PCT/SE2006/001218, filed on Oct. 27, 2006, and claims the benefit of
U.S. Provisional Application No. 60/806,975, filed on Jul. 11, 2006 and
of Swedish Application No. 0601550-7, filed on Jul. 11, 2006. The present
application hereby incorporates herein by reference the subject matter of
U.S. application Ser. No. 11/775,885; U.S. application Ser. No.
10/970,282; U.S. application Ser. No. 11/092,748; PCT/SE2006/001218; U.S.
Provisional Application No. 60/806,975; and Swedish Application No.
0601550-7.

AREA OF INVENTION

[0002] The invention generally relates to the field of floor panels with
mechanical locking systems with a flexible and displaceable tongue. The
invention also relates to a partly bendable tongue for a building panel
with such a mechanical locking system.

BACKGROUND

[0003] In particular, yet not restrictive manner, the invention concerns a
tongue for a floor panel and a set of floor panels mechanically joined to
preferably a floating floor. However, the invention is as well applicable
to building panels in general. More particularly invention relates to the
type of mechanically locking systems comprising a flexible or partly
flexible tongue and/or displaceable tongue, in order to facilitate the
installation of building panels.

[0004] A floor panel of this type is presented in WO2006/043893, which
discloses a floor panel with a locking system comprising a locking
element cooperating with a locking groove, for horizontal locking, and a
flexible tongue cooperating with a tongue groove, for locking in a
vertical direction. The flexible tongue bends in the horizontal plane
during connection of the floor panels and makes it possible to install
the panels by vertical folding or solely by vertical movement. By
"vertical folding" is meant a connection of three panels where a first
and second panel are in a connected state and where a single angling
action connects two perpendicular edges of a new panel, at the same time,
to the first and second panel. Such a connection takes place for example
when a long side of the first panel in a first row is already connected
to a long side of a second panel in a second row. The third panel is then
connected by angling to the long side of the first panel in the first
row. This specific type of angling action, which also connects the short
side of the new panel and second panel, is referred to as "vertical
folding". It is also possible to connect two panels by lowering a whole
panel solely by vertical movement against another panel.

[0005] Similar floor panels are further described in WO2003/016654, which
discloses locking system comprising a tongue with a flexible tab. The
tongue is extending and bending essentially in a vertical direction and
the tip of the tab cooperates with a tongue groove for vertical locking.

Definition of Some Terms

[0006] In the following text, the visible surface of the installed floor
panel is called "front face", while the opposite side of the floor panel,
facing the sub floor, is called "rear face". The edge between the front
and rear face is called "joint edge". By "horizontal plane" is meant a
plane, which extends parallel to the outer part of the surface layer.
Immediately juxtaposed upper parts of two adjacent joint edges of two
joined floor panels together define a "vertical plane" perpendicular to
the horizontal plane.

[0007] By "joint" or "locking system" is meant co-acting connectors or
connecting means, which connect the floor panels vertically and/or
horizontally. By "mechanical locking system" is meant that joining can
take place without glue. Mechanical locking systems can in many cases
also be combined with gluing. By "integrated with" means formed in one
piece with the panel or factory connected to the panel.

[0008] By a "flexible tongue" is meant a separate tongue which has a
length direction along the joint edges and which is forming a part of the
vertical locking system and could be displaced horizontally during
locking. The tongue could be, for example, bendable or have a flexible
and resilient part in such a way that it can bend along its length and
spring back to its initial position.

[0009] By "angling" is meant a connection that occurs by a turning motion,
during which an angular change occurs between two parts that are being
connected, or disconnected. When angling relates to connection of two
floor panels, the angular motion takes place with the upper parts of
joint edges at least partly being in contact with each other, during at
least part of the motion.

SUMMARY

[0010] The present invention relates to a set of floor panels or a
floating flooring and tongue for a floor panel, which provides for new
embodiments according to different aspects offering respective
advantages. Useful areas for the invention are floor panels of any shape
and material e.g. laminate, wood, HDF, veneer or stone.

[0011] According to a first object, an embodiment of the invention
provides for a set of floor panels comprising a front face, a rear face,
and a mechanical locking system at two adjacent edges of a first and a
second panel, whereby the locking system is configured to connect a first
panel to a second panel in the horizontal and vertical plane. The locking
system is provided, in order to facilitate the installation, with a
displaceable tongue for locking in the vertical plane. The tongue is
displaceable in a displacement groove in the edge of one of the floor
panels and is configured to cooperate with a tongue groove in the other
of said floor panels. A first long edge of the tongue comprises at least
two bendable protrusions extending essentially and bendable in the
horizontal plane. A second long edge of the tongue, which in the
connected state extends outside the displacement groove, has an
essentially straight outer edge over substantially the whole length of
the tongue.

[0012] As the floor panel according to the first embodiment of the
invention is provided with a displaceable tongue with bendable
protrusions and an essentially straight outer edge this offers several
advantages. A first advantage consists in that the floor panels are
locked in the vertical direction along substantially the whole length of
the tongue. A second advantage is that it is possible to mould the
tongues in one part in e.g. plastic material and if desired to cut them
up in shorter tongues, which all have essentially the same properties.
The same moulding tool could be used to produce flexible tongues for
different panel widths. Especially the displacement resistance and the
locking strength per length unit could be achieved. A third advantage is
that the displacement resistance, due to the bending of the protrusions,
is essentially the same along the whole tongue. A larger number of
protrusions provides for a more constant displacement resistance along
the edge of the tongue. If the panels are installed by vertical folding a
constant displacement resistance over the length of the tongue is
desired. Also a high angle between the fold panel and the second panel
when the fold panel initially contact the tongue in the second panel is
provided. The protrusions are designed to allow displacement but also to
prevent tilting of the tongue.

[0013] A floor panel is known from WO2006/043893, as mentioned above, and
discloses a bow shaped flexible tongue bendable in the length direction.
The drawback of this bow shaped tongue is that due to the shape, there is
no locking at the end of the tongue. One embodiment is shown that
provides locking along the whole length (FIG. 7f), but that tongue
consists of two connected parts (38, 39). It is also important that the
tongue easily springs back after being displaced into the displacement
groove during installation. Therefore it is advantageously if the part of
the tongue which cooperate with the adjacent panel is relatively stable
and is provided with sliding surfaces with an area enough to avoid that
the tongue get stuck before reaching its final position for vertical
locking. A sliding surface at the tip of a tab or a protrusion is
therefore not a useful solution.

[0014] Advantageously, the protrusions of the tongue are bow shaped,
providing an essentially constant moment arm during installation of the
panels and bending of the protrusions.

[0015] Preferably, the tongue comprises a recess at each protrusion,
resulting in avoiding of deformation and cracking of the protrusion if
the tongue is displaced too far and too much force is applied.

[0016] Preferably, the length of the tongue is of more than 90% of the
width WS of front face of the panel; in other preferred embodiments the
length of the tongue is preferably in the range from 75% to substantially
the same as the width WS of front face.

[0017] A second embodiment of the invention provides for a tongue for a
building panel, said tongue is of an elongated shape and made of molded
plastic. The tongue comprises at least two protrusions at a first long
edge of the tongue. The protrusions are bendable in a plane parallel to
the upper surface of the tongue and extending essentially in the parallel
plane. Furthermore, the tongue has a second long edge, which is
essentially straight over substantially the whole length of the tongue.

[0018] A first advantage consists in that the tongue provides for locking
in the vertical direction along the whole length of the tongue. A second
advantage is that it is possible to mould the tongue in one part in
plastic and if desired cutting the tongue in shorter tongues, which all
have essentially the same properties. Especially the displacement
resistance and the locking strength per length unit are essentially the
same. A third advantage is that the displacement resistance, due to the
bending of the protrusions, is essentially the same along the whole
tongue. A larger number of protrusions provides for a more constant
displacement resistance along the edge of the tongue. Even rather rigid
materials such as reinforced plastic, metals, for example aluminium and
wood may be made flexible with protrusions according to the principle of
the invention. If the panels are installed by vertical folding, e.g. by
the installation method explained below (see FIG. 5), a constant
displacement resistance is desired

[0019] All references to "a/an/the [element, device, component, means,
step, etc]" are to be interpreted openly as referring to at least one
instance of said element, device, component, means, step, etc., unless
explicitly stated otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIGS. 1a-d illustrate a prior art locking system

[0021] FIGS. 2a-b show a prior art flexible tongue during the locking
action.

[0022] FIGS. 3a-b show a floor panels with a prior art mechanical locking
system on a short side.

[0023] FIGS. 4a-b show how short sides of two floor panels could be locked
with vertical folding according to prior art.

[0024] FIGS. 5a-c show panels according to one embodiment of the invention
and a preferred locking method.

[0025] FIGS. 6a-e show displaceable tongues in embodiments according to
the invention.

[0026] FIGS. 7a-b show the displaceable tongues in an embodiment according
to the invention in a top view and a 3D view

[0027] FIGS. 8a-b show the bending of the protrusion of the tongue, during
installation, according to embodiments of the invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0028] As represented in FIGS. 5-8, the disclosure relates to a set of
floor panels with a displaceable tongue and displaceable tongue for a
floor panel.

[0029] A prior art floor panel 1, 1' provided with a mechanical locking
system and a displaceable tongue is described with reference to FIGS.
1a-1d.

[0030] FIG. 1a illustrates schematically a cross-section of a joint
between a short side joint edge 4a of a panel 1 and an opposite short
side joint edge 4b of a second panel 1'.

[0031] The front faces of the panels are essentially positioned in a
common horizontal plane HP, and the upper parts 21, 41 of the joint edges
4a, 4b abut against each other in a vertical plane VP. The mechanical
locking system provides locking of the panels relative to each other in
the vertical direction D1 as well as the horizontal direction D2.

[0032] To provide joining of the two joint edges in the D1 and D2
directions, the edges of the floor panel have in a manner known per se a
locking strip 6 with a locking element 8 in one joint edge, hereafter
referred to as the "strip panel" which cooperates with a locking groove
14 in the other joint edge, hereafter referred to as the "fold panel",
and provides the horizontal locking.

[0033] The prior art mechanical locking system comprises a separate
flexible tongue 30 fixed into a displacement groove 40 formed in one of
the joint edges. The flexible tongue 30 has a groove portion P1, which is
located in the displacement groove 40 and a projecting portion P2
projecting outside the displacement groove 40. The projecting portion P2
of the flexible tongue 30 in one of the joint edges cooperates with a
tongue groove formed in the other joint edge.

[0034] The flexible tongue 30 has a protruding part P2 with a rounded
outer part 31 and a sliding surface 32, which in this embodiment if
formed like a bevel. It has upper 33 and lower 35 tongue displacement
surfaces and an inner part 34.

[0035] The displacement groove 40 has an upper 42 and a lower 46 opening,
which in this embodiment are rounded, a bottom 44 and upper 43 and lower
45 groove displacement surfaces, which preferably are essentially
parallel with the horizontal plane HP.

[0036] The tongue groove 20 has a tongue-locking surface 22, which
cooperates with the flexible tongue 30 and locks the joint edges in a
vertical direction D1. The fold panel 1' has a vertical locking surface
24, which is closer to the rear face 62 than the tongue groove 20. The
vertical locking surface 24 cooperates with the strip 6 and locks the
joint edges in another vertical direction. The fold panel has in this
embodiment a sliding surface 23 which cooperated during locking with the
sliding surface 32 of the tongue.

[0037] FIG. 3a shows a cross section A-A of a panel according to FIG. 3b
seen from above. The flexible tongue 30 has a length L along the joint
edge, a width W parallel to the horizontal plane and perpendicular to the
length L and a thickness T in the vertical direction D1. The sum of the
largest groove portion P1 and the largest protruding part P2 is the total
width TW. The flexible tongue has also in this embodiment a middle
section MS and two edge sections ES adjacent to the middle section. The
size of the protruding part P2 and the groove portion P1 varies in this
embodiment along the length L and the tongue is spaced from the two
corner sections 9a and 9b. The flexible tongue 30 has on one of the edge
sections a friction connection 36 which could be shaped for instance as a
local small vertical protrusion. This friction connection keeps the
flexible tongue in the displacement groove 40 during installation, or
during production, packaging and transport, if the flexible tongue is
integrated with the floor panel at the factory.

[0038] FIGS. 2a and 2b shows the position of the flexible tongue 30 after
the first displacement towards the bottom 44 of the displacement groove
40. The displacement is caused essentially by bending of the flexible
tongue 30 in its length direction L parallel to the width W. This feature
is essential for this prior art.

[0039] The fold panel could be disconnected with a needle shaped tool,
which could be inserted from the corner section 9b into the tongue grove
20 and press the flexible tongue back into the displacement groove 40.
The fold panel could than be angled up while the strip panel is still on
the sub floor. Of course the panels could also be disconnected in the
traditional way.

[0040] FIGS. 4a and 4b show one embodiment of a vertical folding. A first
panel 1'' in a first row is connected to a second 1 panel in a second
row. The new panel 1' is connected with its long side 5a to the long side
5b of the first panel with angling. This angling action also connects the
short side 4b of the new pane with the short side 4a of the second panel.
The fold panel 1' is locked to the strip panel 1 with a combined vertical
and turning motion along the vertical plane VP. The protruding part P2
has a rounded and or angled folding part P2' which during folding
cooperates with the sliding surface 23 of the folding panel 1'. The
combined effect of a folding part P2', and a sliding surface 32 of the
tongue which during the folding cooperates with the sliding surface 23 of
the fold panel 1' facilitates the first displacement of the flexible
tongue 30. An essential feature of this embodiment is the position of the
projecting portion P2, which is spaced from the corner section 9a and 9b.
The spacing is at least 10% of the length of the joint edge, in this case
the visible short side 4a.

[0041] FIGS. 5a-5c show an embodiment of the set of floor panels with a
displaceable tongue according to the invention and a preferred
installation method. In this embodiment the length of the tongue is of
more than 90% of the width WS of front face of the panel, in other
preferred embodiments the length of the tongue is preferably in the range
from 75% to substantially the same as the width WS of front face.
Preferably, the length of the tongue is about the total width of the
panel minus the width of the locking system of the adjacent edges of the
panel. A small bevel may be provided at the ends of the outer edge, but
the straight part of the tongue at the outer edge has preferably a length
substantially equal to the length of the tongue or desirably more than
90%. The new panel 1' is in angled position with an upper part of the
joint edge in contact with the first panel 1'' in the first row. The new
panel 1' is then displaced towards the second panel 1 until the edges are
essentially in contact and a part of the flexible tongue 15 is pressed
into the displacement groove 40 as can be seen in the FIG. 5b. The new
panel 1' is then folded down towards the second panel 1. Since the
displacement of the new panel 1' presses only an edge section of the
flexible tongue 30 into the displacement groove 40, vertical folding will
be possible to make with less resistance. Installation could be made with
a displaceable tongue that has a straight outer edge. When panels with
the known bow shaped tongue 30 (see FIGS. 2-4) are installed the whole
tongue has to be pressed into the displacement groove. When comparing the
known bow shaped tongue with a tongue according to the invention less
force is needed for a tongue with the same spring constant per length
unit of the tongue. It is therefore possible, using the principles of the
invention, to use a tongue with higher spring constant per length unit
and higher spring back force, resulting in more reliable final position
of the tongue. With this installation method the beveled sliding surface
of the fold panel is not necessary, or may be smaller, which is an
advantage for thin panels. If the tongue is not long enough, the
installation method above is not working and the beveled sliding surface
of the fold panel is needed. FIG. 5c show that the tongue could be on the
folding panel.

[0042] A preferred production method according to the invention is
injection moulding. With this production method a wide variety of complex
three-dimensional shapes could be produced at low cost and the flexible
tongues 30 may easily be connected to each other to form tongue blanks. A
tongue could also be made of an extruded or machined plastic or metal
section, which could be further shaped with for example punching to form
a flexible tongue according to the invention. The drawback with
extrusion, besides the additional productions steps, is that it is hard
to reinforce the tongue, e.g. by fibres.

[0043] As can be seen when comparing FIGS. 5 and 4, the angle between the
new panel 1 and the second panel 1 is higher, for the panels with the
tongue according to an embodiment of the invention, when the new panel
initially contacts the end of the tongue 30 and begins to displace the
tongue into the displacement groove 40. It is an advantage if the angle
is higher, since a higher angle means a more comfortable working position
in which it is easier to apply a higher force pushing the tongue into the
displacement groove.

[0044] Any type of polymer materials could be used such as PA (nylon),
polyoxymethylene (POM), polycarbonate (PC), polypropylene (PP),
polyethyleneterephthalate (PET) or polyethylene (PE) or similar having
the properties described above in the different embodiments. These
plastic materials could be when injection moulding is used be reinforced
with for instance glass fibre, Kevlar fibre, carbon fibre or talk or
chalk. A preferred material is glass fibre, preferably extra long,
reinforced PP or POM.

[0045] FIGS. 6a-e shows embodiments of the tongue 15 according to the
invention. They are all configured to be inserted in a groove in a floor
panel, in a similar way as described for the prior art tongues and panels
in reference to FIGS. 1-4 above. All methods to injection mould, insert
and also the tool for disassembling described in WO2006/043893 and partly
in the description and FIGS. 1-4 above are applicable to the invention.

[0046] FIG. 6a shows an embodiment with a first long edge L1 and a second
long edge L2. The first long edge has protrusions extending in a plane
parallel to the topside 64 of the tongue 30 and with an angle relative
the longitudinal direction of the tongue.

[0047] FIGS. 6a-b show the embodiment, in top and in a side view, with a
first long edge L1 and a second long edge L2. The first long edge has
protrusions 61 extending in a plane parallel to the topside, an upper
displacement surface, and rear side, a lower displacement surface, of the
tongue and with an angle relative the longitudinal direction of the
tongue. The protrusions are preferably bow shaped and, in a particular
preferred embodiment, the tongue is provided with a recess 62 at each
protrusion 61. The recess is preferably adapted to the size and shape of
the protrusion.

[0048] The protrusions are preferably provided with a friction connection
63, most preferably close to or at the tip of the protrusion, which could
be shaped for instance as a local small vertical protrusion. This
friction connection keeps the flexible tongue in the displacement groove
40 during installation, or during production, packaging and transport, if
the displaceable tongue is integrated with the floor panel at the
factory.

[0049] FIG. 6d shows the tongue in the cross section B-B in FIG. 6c and
positioned in the displacement groove 40 of a panel 1. The upper and
lower displacement surface of the tongue is configured to cooperate with
an upper 43 and a lower 45 groove displacement surfaces. The panel
comprising a locking strip 6 and a locking element 8 for horizontal
locking. The panel 1 is configured to be connected to a second panel 1'
in a similar way as the prior art panel 1' in FIG. 1a-1d. The upper
displacement surface (64) and/or the lower displacement surface (65) of
the tongue is in one preferred embodiment provided with a beveled edge,
presenting an upper sliding surface (32) and lower sliding surface (31),
and an inclined locking surface (66), respectively. The inclined locking
surface cooperates preferably with an inclined tongue-locking surface 22
in the tongue groove (20).

[0050] In embodiments according to FIGS. 6d and 6e, the displacement
groove (40) is formed in one piece with the core of the panel, but other
alternatives are possible. The displacement groove may be formed in a
separate material, for example HDF, which is connected to a wood core in
a parquet floor. The displacement grove may be formed of U-shaped plastic
or metal sections, which are connected to the panel with for example a
snap connection, glue or friction. These alternatives could be used to
reduce friction and to facilitate horizontal displacement of the tongue
in the displacement grove. The displacement groove may also be treated
with a friction reducing agent. These principles may also be applied to
the tongue groove.

[0051] FIG. 6e shows that the tongue 30 may also be inserted into the
displacement groove 40 of a panel for locking in the horizontal plane.
The tongue is displaced in the vertical plane during connection of the
panels. These types of panels are connected by a movement in the
horizontal plane--"horizontal snapping".

[0052] To facilitate the installation it is advantageous if the spring
constant of the protruding part is as linear as possible. A linear spring
constant results in a nice and smooth connection movement without
suddenly or heavily increased displacement resistant. According to one
embodiment, this is achieved by a bow shaped protrusion. FIG. 8b shows
that a bow shaped protrusion results in an essentially constant moment
arm, the force is during the whole course of connecting two panels at the
tip of the protrusion, and an essentially linear spring constant. FIG. 8a
shows that a straight protrusion results in that the moment arm is
changed during the course; the force is spread out over a larger part of
the length of the protrusion, resulting in an increased spring constant
during the course. F is the displacement force and L is the displaced
distance.

[0053] The preferred recess at the protrusion has the advantage that the
protrusion is not destroyed if too much force is applied or the tongue is
displaced too far. The protrusion is pushed into the recess and a
cracking of the protrusion is avoided.

[0054] FIGS. 7a-b show two enlarged embodiments of a part of the tongue in
a top view and in a 3D view. The figures show a casting gate 71 which is
cut off before insertion into the displacement groove.

[0055] It is preferred that the length of the protrusion PL is larger than
the total width TW of the tongue. The total width is the width of the
tongue W plus the distance from the tongue body to the tip of the
protrusion perpendicular to the length direction of the tongue. In the
most preferred embodiment, PL is larger than 2*TW. It is also preferred
that the recess is wider near the tip of the protrusion than near the
bottom of the recess; as shown 1 FIG. 7a.

[0056] Preferably, the force to displace the tongue 1 mm is per 100 mm
length of the tongue in the range of about 20 to about 30 N.

[0057] Preferably the length of the protrusion PL is in the range of about
10 mm to about 20 mm, the width W of the tongue is in the range of about
3 mm to about 6 mm and the total width TW of the tongue is in the range
of about 5 mm to about 11 mm. The length of the body part BP between two
protrusions, i.e. the distance from the root of one protrusion to the tip
of an adjacent protrusion, is in the range of about 3 mm to about 10 mm.
As a non limiting example, for a width of a floor panel of about 200 mm,
including the width of the locking system at adjacent edges, with a
tongue length of about 180 mm, having 9 protrusions the protrusion length
is about 15 mm, the length of the body part BP is about 5 mm, the width
of the tongue W is about 5 mm and the total width TW is about 8 mm.

[0058] The tongues according to the embodiments of the invention are all
possible to mould in one piece. It is further possible to cut the molded
tongue in shorter pieces which all have the same properties per length
unit, provided that the number of protrusions is not too few.